Johanna Maria van der Gheynst (also called Jeanne Marie van der Gheynst, Johanna Maria van der Gheenst; c. 1500 - 15 December 1541) was in 1521-1522, for a short time, the mistress of the Emperor Charles V and bore him a daughter, Margaret of Parma, who was Governor of the Netherlands from 1559 to 1567 and from 1580 to 1583.

Johanna Maria van der Gheynst was the daughter of the carpetmanufacturer Gilles Johan van der Gheynst and his wife Johanna van der Caye van Cocambi. Her parents lived at Nukerke near Oudenaarde. She entered the service of Charles I de Lalaing, Governor of Oudenaarde and Seigneur of Montigny.

The young Emperor Charles V met the beautiful Johanna, when he visited the castle of the Seigneur of Montigny in autumn 1521. Their short love affair produced a daughter who was named Margaret and put in the care of the Brussels family de Douvrin. Charles V did not conceal his liaison with Johanna and in July 1529 he acknowledged Margaret as his daughter. Margaret was to become Governor of the Netherlands.

The Emperor granted Johanna van der Gheynst a modest pension. On 13 October 1525 she married Jean van den Dyke, a jurist and member of the audit office of Brabant. The couple had several children. Johanna died in 1541, her husband on 1 September 1572.